Safety lifting jack



D. C. KLAUSMEYER. SAFETY LIFTING JACK. APPLICATION FILED MAYIO I Patented May 23, 1922.

' INVENTOR Q ATTORNEY N l E DAVID C. KLAUSIVIEYER, 0F CINCINNATI, OHIO, ASSIGNOR TO TI-IE CINCINNATI BICKFORD TOOL COMPANY, OF OAKLEY, CINCINNATI, OHIO, A CORPORATION OF OHIO.

SAFETY LIFTING JACK.

i Maasai.

i Application led May 10,

To all whom t may concern.'

Be it known that I, DAVID C. KLAUS- MEYER, a citizen of the United States, and residing at Cincinnati, in the county of Hamilton and State of Ohio, have invented a new and Improved Safety Lifting Jack,

of which the following specification is a full disclosure.

This invention relates to lifting acks and has more special reference to a lifting ack characterized by the provision of safety means for avoiding accident through the collapse of the jack due to the failure of the usual load sustaining parts. These load sustaining parts, in thespecific embodiment illustrated, take the form of the conventional screw and nut. A stripping of the threads of the screw and nut may result when a load exceeding the sustaining capacity of the threads is applied to the jack. Then the parts are new, the danger of collapse of the jack is comparatively remote because ordinarily7 the applied load will be well within the designed capacity of the jack. After the jack has been in use for some time, however, the threads of the nut and screw may becomeworn to such an eX- tent that the jack may collapse even if a load considerably less than the designed capacity is applied.

An object of this invention is to guard against the possibility of collapse and is accomplished by providing an auxiliary member which does not function in the ordinary operation of the jack, thereby obviating its thread wear, so that the load may be carried by its unused and unworn threads; if the threads, which ordinarily serve to sustain the load, fail.V

The drawing exemplifies the essentials of the invention.

Fig. l is a general view of the jack mechanism.

Figure 2 is a sectionalvie'won a central vertical plane through Fig. l.

Fig. 3 is a sectional view on the line 3--3 of Fig. 2.

In said drawing the part A indicates the base of the lifting jack. While the particular shape of this base forms no part of the invention, nevertheless it is characterized by the provision of a vertical opening A', having a restricted portion A to a'ord a ledge or abutment on which the movable Specification of Letters Patent.

Patented ltlay 233, 19222. 1921. Scral No. 468,301.

parts of the jack are temporarily sustained, inthe event of the failure of the load sustaining parts. A nut B is held against rotation in this vertical opening A by a set screw B, and rests on a shouldered portion of the base A', although this special support for the nut B is of course not absolutely essential, since it may be adequately supported by increasing the size of the set screws. Furthermore the nut B might be cast integral with the base Aand the invention contemplates such construction as within its intended scope. Irrespective of whether the nut is cast with the table or is a separate entity, a vertical screw C is in threaded engagement with it and serves to nove the object to be raised relatively7 to the base A. The upper end of this vertical screw terminates in a stub shaft having an annular groove C, the latter being engaged by the end of a screw D which passes through a bearing member D. The member D preferably has its upper face corrugated in the manner illustrated to afford a non slip surface to support the work. While the `preferred constructional form utilizes a bearing member D as indicated, nevertheless, it is to be understood that the end of the screw might under certain circumstances directly engage the object to be lifted; or the preferred construction illustrated in the drawing, might be further modified by providing ball bearings to reduce the friction between the bearingmember D Vand the end of the vertical shaft to a minimum. inasmuch as the relative movement of the bearing plate D and the base A is accomplished by the rotation of the screw C and its consequent translationY with respect to nutvB effected an organization for rotating the screw is essential. The screw C may be conveniently rotated by the construction shown in the drawings, in which a capstan head E, having a plurality of openings E each of which is adapted to receive a capstan bar may be manually rotated, This capstan head is secured to the screw in any convenient manner, for example, by tapping an opening in the screw and in the capstan head and driving a pin or threading screw into this opei'iing. l/hile the screw C may be manually driven in the manner just indicated, nevertheless it is to be understood that a power drive,

sov

might be utilized, for example, by splining a worm wheel to an extension shaft secured to the 'lower end of the screw C.

4In* order'to prevent the screw C from dropping down through the nut B, due to the stripping of the threads, an auxiliary safety colla-r or nut F is threaded on the screw C and is so proportioned as to support this screw, in case the aforesaid stripping of the threads occurs. The collar F has a connecting part adapted to cooperate with the nut B which preferably takes the form of an upstanding tongue F adapted to engage a slot (i in the nut B when the parts are in normal position, that is, when the threads of: thenut B and the screw C are meshing properly. The preservation of thethrea'ds of the auxiliary collar is accomplished by slightly spacing the collar from thenut B, so that it rides idly on the screw "C, and, due to the connection indicated, is held stationary by the nut B, without, 1n' `any way, partaking in the support of the load. Solong as the threads of the nut B are properly wfunctioning withthe threads of the screw C; the collar F, through its connection with the nut B, maintains the initial spaced relative position with respect thereto. lf, however, due to a. stripping of the threads, the screw C moves downwardly through the nut B, the auxiliary safety nut F will become separated from the nut B andthe connect-ing tongue disengaged from itsv socket. lf the rotation of the vscrew C is continued after this disengagement occurs as may well be the case, the auxiliary safety nut F will rotate with the screw C preferably riding on the ball bearing cage Cf of the ball'bearings H, which are carried on the shouldered portion A ofthe base A.

Evidentlythe nut F might ride directly on -lb'all bearings which ride only in a lower race.V irrespective of the manner in which tliedrop of the safety nutis stopped, itis desirable to make vthe fall as small as possible, and to this end the abutment or ledge islopcated as near to the nut B as possible and yet sufliciently spaced so as to permitY disengagement of the tongue from the socket.

-In this connection it is to be observed thatthe tongue ina-y be comparatively short inasmuch as but little shear must be resisted.

, Inasmu'chas the threads of the auxiliary nut are unworn and inasmuch as it freely rotates with the screw C, it will temporarily sustain a comparatively heavy load, even though the usual load sustaining threads of the screw C, are entirely stripped.

Evidently the length of the collar F may be increased in proportion to the 'length of.

the threaded part of the nut, so that the collar will be capable of supporting any desired weightV and any degree of safety may be afforded within certain limits, as will be readily understood.

mally sustains the load and the other ofV which is adapted to sustain the load on the failure of the other element of said pair.

2. A lifting jack of the nature disclosed combining a pair of cooperating relatively rotatable load sustaining elements and a safety member adapted to idly cooperate with one of said memberswhen said load sustaining elements are working normally and adapted to sustain the load on the failure of the load sustaining elements.

3. A lifting jack of the nature disclosed combining a rotatable screw; a stationary part in threaded engagement with said screw; and a member slightly spaced from said threaded part held stationary thereby andr adapted to receive the thrust thereof iiithe event of the failure of t-he nut.

4. A lifting jack combining' two separable members, one of which-.constitutes the base; a screw cooperating with these members; and a stationary safety collar in threaded engagement with said screw and having a connection for holding it relatively stationary `to a portion of the base, said connection being separable during any untoward translation of said screw, the safetycollar being adapted to arrest further translation of the screw by abutting` against a portion of the base. 1

5. A lifting jack comprising two members one of which constitutesthe base and the other the carrier of the object; a nut secured to the one constituting the base and a screw vjournalled to the other; a safetyV collar threaded von saidV screw in proximity with said nut and positioned adjacent an abutment in the base, and a detachable connection vbetween the collar and nut adapted normally to cause the collar to remain stationary.

6. A safety lifting-jack combining a stationary memberin the. nature of a base and Y said restraint and enable said jo-urnaled nut to rotate .as a unit with said screw whereby the raised member may be supported but not further elevated by said journaled nut notwithstanding' a continued rotation of 'said screw. Y

17. A safety .lifting-j ack combining anelevatable member and a stationary base; a

screw rotatably secured to the elevatable member; a nut rotatively seated in the base; means non-rotatably related to said base nor- Inally operative on said nut to prohibit its rotation, said means being adapted under abnormal conditions to permit said nut to rotate as a unit with said screw; and a ballbearing underlying said nut and adapted to receive the downward thrust between said nut and the base so as to promote the rotation of said nut when permitted by said nonrotatable means.

8. A safety lifting-jack combiningI a stationary base and an elevatable member; a nut seated in an upright socket in said base; an anti-friction thrustfbearing interposed between said nut and a shoulder at the lower end of said socket; a tubular element arranged concentrically with the nut and nonrotatably connected to said base and normally engaging said nut to prevent rotation thereof, said nut and element being adapted to become disengaged under abnormal conditions to permit said nut to rotate freely; and a lifting-screw rotatably connected to the elevatable member and threaded through said nut.

9. A safety lifting-j ack combining a socketed base providing an annular seat; an annular anti-friction thrust-bearing resting on said seat; a tubular element non-rotatably secured to said base and providing a clutchlike portion spaced from said thrust bearing; a nut intervening between said thrust-bearing and said element and having its up per end formed clutch-like and normally clutched to said element so as to be prevented thereby from rotating; an elevatable cap; and a screw having its upper end rotatably secured to said cap and extending successivel7 through the bores of said element, said nut and said thrustebearing and adapted to cooperate with said parts to effect a shift of one of said clutch-like parts; the construction being such that under abnormal conditions said element and said nut will become cle-clutched to' permit said nut to rotate as a unit with said screw while resting on said anti-friction thrust-bearing and thereby render the screw impotent to effect a further elevation of said cap.

10. A safety lifting-jack combining a base having a socket; an anti-friction thrust-bearing shouldered against the lower end oi' said socket, a iirst tubular part non-rotatably secured tosaid member; a second tubular part located in said socket and having its lower end adjacent said thrust-bearing and having its upper end engaging said tirst part so as to be held thereby against rotation, one of said parts being adapted under abnormal conditions to shift axially sufficiently to disengage the other part and permit the second part to rotate; and a rotatably mounted lifting-screw threaded through said second part and adapted to effect a rotation thereof while being supported by said anti-friction bearing when said second part is dis-connected from said first part and thereby render said rotating lifting-screw impotent to feed through said second part.

In witness whereof, hereunto subscribe my name7 as attested by the two subscribing witnesses.

DAVID C. KLAUS-MEYER. Witnesses AUG. H. TUECHNER, C. C. SLETF.. 

